Resonant Two-Photon Transitions

P. F. Liao, John E. Bjorkholm

Minhua Zhang

Based on the second-order perturbation theory,the two-photon processes in the atom system excited by a shaped chirped-pulse are analyzed.The evolution of the two-photon transition probability is studied under the two cases of non-resonance and resonance.It′s shown that the transition probabilities disappeared at some corresponding frequencies under the non-resonance case,and thus the laser pulse can get through the medium without loss. Meanwhile,the maximum two-photon transition probability is obtained by choosing the best shaping function under the resonance case.

N. D. Voropaev, А. Н. Ораевский

N. A. Enaki, Tudor Roşca

The two-photon and scattering resonances between the spontaneous emissions of the two- and single- photon transitions of the three-level inverted radiators in the Ξ, V configurations and the system of two-level radiators D, inverted relatively the dipole forbidden transition are revised. This approach opens the new possibilities in the manipulation of the decay process and generation of the entangled photon pairs. The correlation between the V and Ξ cascade three-level subsystems on the two-photon transitions of dipole forbidden radiators is studied, taking into consideration the cooperative scattering and two photon resonances through the vacuum field. One of them corresponds to the situation when the total energy of emitted photons by three level dipole-active radiator in the cascade configuration enters into the two-photon resonance with the dipole-forbidden transitions of second atom. Another effect corresponds to the scattering situation, when the difference of the excited energies of the two dipole-active transitions of V three level radiator are in the resonance with the dipole-forbidden transitions of the second one. These effects are accompanied with the interferences between single- and two-quantum collective transitions of the inverted radiators from the ensemble. The two particle collective decay rate is defined in the description of the atomic correlation functions.

P. L. Knight

Lloyd Armstrong, P. Lambropoulos, N. K. Rahman

The effect of photon correlations (coherence) on the transition probability of resonant two-photon processes is discussed. It is shown that coherence influences not only the transition probability but also the linewidth of the resonance. The implications for higher-order multiphoton ionization are discussed.